Mark Dickinson added the comment: Yep, there's an oddity here that's directly inherited from C's sprintf family of functions, namely that in %e-style formatting you give the number of digits after the point (= one less than the total number of significant digits), and in %g-style formatting you give the total number of significant digits instead. Can you give a pointer, or link, to the documentation section you were looking at? The description at: http://docs.python.org/library/stdtypes.html#string-formatting-operations looks fine to me. Note 3, which relates to the '%e' and '%f'-style formatting, talks about number of places after the point. Note 4, which relates to '%g' formatting, talks about the total number of significant digits. ---------- nosy: +mark.dickinson _______________________________________ Python tracker http://bugs.python.org/issue13433 _______________________________________

Mark Dickinson added the comment:

Maybe a note describing that %g is different from the others in this regard?

-1 from me; I don't really see that that would improve the documentation. Maybe that's just me, but I expect reference documentation to be clean, and uncluttered with too many warnings. All the necessary information is already there, and adding extra notes like this just increases the total number of words to be read without adding new information. In a tutorial, that would be different ... :-) Leaving this open---others may have different takes on this. ---------- _______________________________________ Python tracker http://bugs.python.org/issue13433 _______________________________________

Changes by Mark Dickinson : ---------- versions: +Python 3.2, Python 3.3 -Python 2.6 _______________________________________ Python tracker http://bugs.python.org/issue13433 _______________________________________

Christian Iversen added the comment: Certainly, I don't think we should be peppering the docs with warnings and notes, either. However, the elements in question _already have_ notes. I propose that the note for %g (4) simply be updated for clarity. Something like this, perhaps: """Unlike the other floating-point formats, the precision determines the number of significant digits before and after the decimal point and defaults to 6.""" Simply adding "Unlike the other floating-point formats," at the beginning of the second line makes it much clearer that this is a different beast. If you feel that is not the right solution, then feel free to close this issue. ---------- _______________________________________ Python tracker http://bugs.python.org/issue13433 _______________________________________

Christian Iversen added the comment: Terry, the %g format always trims trailing zeroes, so you'd have to try with a number that doesn't end in zero. I had to make a re-implementation of format for javascript: http://paste.pocoo.org/show/513078/ If you look at the %g case, you can clearly see how much more complex and different it is, not that that itself indicates a bug. But it is different for sure :) ---------- _______________________________________ Python tracker http://bugs.python.org/issue13433 _______________________________________

Mark Dickinson added the comment: Closing; the documentation was updated recently. See #39096 for details. ---------- resolution: -> fixed stage: -> resolved status: open -> closed _______________________________________ Python tracker https://bugs.python.org/issue13433 _______________________________________